1. Field of the Invention
The present invention relates to a solid-state image sensor, and an image sensing apparatus including the same.
2. Description of the Related Art
In recent years, a solid-state image sensor built into a digital camera must have a function which can sense not only a still image but also a moving image. While the number of pixels of a still image increases each generation, the number of pixels of a moving image is 1,920 in the horizontal direction and 1,080 in the vertical direction at present even if the moving image has a highest resolution. This means that a still image has a number of pixels far greater than a moving image. Hence, it is a common practice to select different numbers of pixels to be processed between still image sensing and moving image sensing. More specifically, it is a common practice in moving image sensing to add or average outputs from a plurality of pixels and use the sum or the average as an output from one pixel.
Japanese Patent Laid-Open No. 2005-244995 proposes a method of sharing a common floating diffusion (FD) between two or more pixels, which output identical color signals, among pixels of three colors: R, G, and B, and adding signals from the plurality of pixels by the FD.
In the color arrangement of, for example, a primary color filter or a complementary color filter, pixels of the same color are arranged every other pixel in the row and column directions. Therefore, when a common FD is shared using the method described in Japanese Patent Laid-Open No. 2005-244995, a wiring pattern for one color for use in sharing intersects with an adjacent wiring pattern for another color. This intersection causes outputs from pixels of different colors to capacitively couple with each other, thus leading to crosstalk. The crosstalk increases noise, so the signal-to-noise ratio (S/N) decreases.